Omega OME-A822PG manual A/D Conversion

2.7 A/D Conversion

This section explains how to perform A/D conversions. The A/D conversion can be triggered 3 ways, by software trigger, by pacer trigger or by external trigger to the A/D converter. At the end of A/D conversion, it is possible to transfer data by 3 ways, those are polling , interrupt and DMA. Before using the A/D conversion functions, the user should be aware of the following issues:

zA/D data register BASE+4/BASE+5 stores the A/D conversion data (sec. 2.4.2)

zA/D gain control register BASE+9 selects the gain (sec. 2.4.6)

zA/D multiplexer control register BASE+A selects the analog input channel (sec. 2.4.7)

zA/D mode control register BASE+B selects the trigger type and transfer type (sec. 2.4.8)

zA/D software trigger control register is BASE+C (sec. 2.4.9)

zJP3 selects single-ended or differential input (sec. 2.3.3)

zJP4 selects internal/external trigger (sec. 2.3.4)

zJP5 selects the IRQ level (sec. 2.3.5)

zJP6 selects the internal/external clock for counter0 (sec. 2.3.6)

zJP7 and JP8 selects the DMA channel (sec. 2.3.7)

zThere are 3 trigger types : software, pacer, external trigger (sec. 2.4.8)

zThere are 3 transfer types : polling, interrupt, DMA (sec. 2.4.8)

The block diagram is given below:

CN3	16/8 to 1	Gain	12 bits
	Multi-	control	A/D		Buffer		Memory
	plexer
	Base+A	Base+9	Trigger		Transfer		CPU
			Logic		Logic
	JP3	Base+C	JP4	Base+B		JP5
OME-A-822PGL/PGH						JP7
						JP8
	OME-A-822PGL/PGH Hardware Manual					---- 27